United States: A Chemical Markush Claim Tests The Elasticity Of "Consisting Of"

Why are chemical patent claims so difficult to understand? This
was the question posed during a 1961 presentation before the
Division of Chemical Literature for the American Chemical Society.
According to the author, "[A]ttention has been called to the
'sometimes baffling' and seemingly 'absurd' idiom
in which are cast chemical patent claims."1 At
least some of the blame for the confusion was attributed by the
author to the "so-called 'Markush'
claim."2 Thus, the author wisely advised,
"[A]n understanding of the philosophy behind the Markush
expression in chemical claims might help to understand better the
meaning of chemical claims themselves."3 More than
fifty years later, and at a time where subject matter eligibility,
written description, and definiteness issues are at the forefront
of the patent prosecution sphere, the Federal Circuit's
decision in Multilayer Stretch Cling Film Holdings, Inc. v.
Berry Plastics Corp., Nos. 2015-1420, -1477 (Fed. Cir. Aug. 4,
2016), revisits the Markush claims and offers guidance on their
proper use.

In Ex parte Markush, 1925 C.D. 126 (Comm'r Pat.
1924), the Commissioner of Patents held that "where no generic
expression exists by which a group of alternative elements can be
claimed applicants are permitted to recite the elements in the
alternative." Thus, "[a] Markush claim is a particular
kind of patent claim that lists alternative species or elements
that can be selected as part of the claimed
invention." Multilayer Stretch, slip op. at 10.
Although the concept can be extended to various technologies,
traditionally, Markush claims have been more prevalent in the
chemical arts, where a Markush claim often recites the presence of
a specific substituent selected from a recited group of
chemicals.

No precise linguistic formula is required to create a Markush
claim. See, e.g., id. The guidelines for patent
examination are instructive on this point, providing that the
'[a]lternative expressions are permitted' so long as the
claim 'recites a list of alternatively useable species'
with no 'uncertainty or ambiguity with respect to the question
of scope or clarity of the claims.' Id.
(alteration in original) (quoting MPEP § 2173.05(h)). The
Federal Circuit has also explained that "[a] Markush group,
incorporated in a claim, should be 'closed,' i.e. it must
be characterized with the transition phrase 'consisting
of,' rather than 'comprising' or
'including.'" Abbott Labs. v. Baxter Pharm.
Prods., Inc., 334 F.3d 1274, 1280-81 (Fed. Cir. 2003)
(alteration in original) (citation omitted)). In
MultilayerStretch, the Federal Circuit addressed
the proper scope of Markush claims by looking at two different ways
in which the term "consisting of" was used in the claims
at issue.

At issue in the case were patent claims directed to multilayered
thermoplastic stretch wrap films. In particular, the Federal
Circuit was asked to weigh in on the proper construction of clause
(b) of independent claim 1 and similarly worded independent claim
28. Claim 1 is
representative:
"(b) five identifiable inner layers, with
each layer being selected from the group consisting
of linear low density polyethylene [LLDPE], very low
density polyethylene [VLDPE], ultra low density polyethylene
[ULDPE], and metallocene-catalyzed linear low density polyethylene
[mLDPPE] resins; said resins are homopolymers, copolymers, or
terpolymers, of ethylene and C3 to C20
alpha-olefins...."
Dependent claim 10, which recites, in relevant part, "[t]he
multi-layer, thermoplastic stretch wrap film of claim 1, where at
least one said inner layer comprises low density polyethylene
homopolymers [LDPE]," was also addressed.

Element (b) essentially creates a Markush group that lists four
species or types of resin—LLDPE, VLDPE, ULDPE, and
mLLDPE—understood to be alternately useable as "inner
layers" of the claimed film. The district court construed the
claim to require that each of the five layers of the film be
composed of only one of the four listed resins (i.e., excluding
layers made of blends of the recited resins). Id. at 2.
Following this construction, the district court granted summary
judgment of noninfringement, as at least one inner layer of the
accused films contained blends of resins from the class of mLLDPE,
ULDPE, and LLDPE, a fact that both parties agreed on. See
id. at 8. The district court further invalidated claim 1,
finding that it was closed to resins other than the ones explicitly
recited in the Markush group. In addressing the issue of claim
construction, the Federal Circuit dealt with two issues: (1)
whether the Markush group of element (b) is closed to
resins other than the listed four, and (2) whether the
Markush group is closed to blends of the four listed
resins. Id. at 11. In short, the Federal Circuit
answered "yes" to the first question (over the dissent of
Judge Taranto) and "no" to the second question.

On the first issue, the Federal Circuit reiterated that the use
of the transitional phrase "consisting of" to set off a
patent claim element creates a very strong presumption that the
claim element is "closed" and therefore "exclude[s]
any elements, steps, or ingredients not specified in the
claim." Id. at 12 (alteration in original)
(quoting AFG Indus., Inc. v. Cardinal IG Co., 239 F.3d
1239, 1245 (Fed. Cir. 2001)).. "'[I]t is not inconceivable
that a patentee could break with conventional claim construction
and become his own lexicographer,' so as to give [the term]
'consisting of' an alternative, less restrictive
meaning." Id. (quoting Conoco, Inc., v. Energy
& Envtl. Int'l, L.C., 460 F.3d 1349, 1359 n.4 (Fed.
Cir. 2006). "But to overcome the exceptionally strong
presumption that a claim term set off with 'consisting of'
is closed to unrecited elements, the specification and prosecution
history must unmistakably manifest an alternative meaning."
Id.

Multilayer argued that this alternative meaning was communicated
in the patent. But rather than arguing that the specification
of the patent indeed had an unmistakable intent to open element (b)
to any unrecited resin, Multilayer's argument was more
focused. In particular, Multilayer argued that the claimed inner
layers should be open to one resin specifically claimed in its
dependent claims (i.e., low density polyethylene (LDPE)).
Id. at 14-15. A closed interpretation of claim 1,
Multilayer argued, would be improper as the Court should
"strive[ ] to reach a claim construction that does not render
claim language in dependent claims
meaningless." Id. at 16 (alteration in original)
(quoting Ortho-McNeil Pharm., Inc. v. Mylan Labs., Inc.,
520 F.3d 1358, 1362 (Fed. Cir. 2008)). The court rejected
Multilayer's position, noting that while dependent claims can
provide guidance in the proper interpretation of the scope of an
independent claim, "[t]he dependent claim tail cannot wag the
independent claim dog." Id. (quoting N. Am.
Vaccine, Inc. v. Am. Cyanamid Co., 7 F.3d 1571, 1577 (Fed.
Cir. 1993)).

Consistently, the court found that the specification did not
provide "a clear intent to open the Markush group of element
(b) to LDPE or to any other resin not expressly listed in the
claim." Id. at 15. With this finding, the dependent
claims that claim inner films with resins other than those four
recited in claim 1, including LDPE, also were held invalid.

Dissenting, Judge Taranto focused on the fact that the language
in the claim was not a classic Markush claim, as the term preceding
the listing was not representative of the generic type of elements
recited within the group. In particular, Judge Taranto argued that
a "layer" is an open-ended physical structure that does
not "have to be one or more of the listed
species" of resins. Taranto Dissent at 4. If the
claim had said "layer consisting of" one or more of the
listed resins, Judge Taranto explained, the meaning would have been
plain, as it would have conveyed that the layer must be made out of
only the listed resins, and not others. Id. at 2-3.
However, the language actually used in the claims is a step
removed. In element (b), "consisting of" does not follow
and directly modify "layer"; it follows and directly
modifies "group." Id. at 2. Thus, the
phrase characterizes the relationship between "group" and
the listed resins: the latter are all the members of the
former. Id. It does not characterize the (closed or
open) relationship between "layer" and what materials can
be ingredients of the layer. Id. The claim phrase
naming that relationship is "selected from," not
"consisting of." Id. at 2-3. The established
meaning of "consisting of" therefore does not determine
the meaning of the claim language here.
Id at 3.

On the second question, i.e., whether limitation (b) of claims 1
and 28 is closed to blends of LLDPE, VLDPE, ULDPE, and mLLDPE, the
Federal Circuit agreed with Multilayer that the Markush group of
element (b) must be construed to permit blends of the four recited
resins. Multilayer Stretch, slip op at 21-22
(majority opinion). Drawing a distinction with the use of
"consisting of" discussed in the first question, the
Federal Circuit noted that the use of the transitional phrase
"consisting of," by itself, does not necessarily suggest
that a Markush group is closed to mixtures, combinations, or
blends. Id. at 22. Nonetheless, there is a presumption
that a Markush group is closed to mixtures of the listed elements.
Id. (citing Abbott, 334 F.3d at 1281). If a
patentee desires mixtures or combinations of the members of the
Markush group, the patentee would need to add qualifying language
while drafting the claim. Id. Here, there is no
express language in element (b) permitting "mixtures,"
"combinations," or "blends" of the four recited
resins; thus, under Abbott, the Markush group of element
(b) is therefore presumed closed to blends. Id. at
22-23. The question is whether that presumption can be
overcome by a combination of other claim language and the
specification itself. Id. at 23.

On this point, the Federal Circuit found that Multilayer had
rebutted the presumption of excluding blends of the resins. The
intrinsic evidence of the patent, in the claims and the
specification, is unequivocal that the inner layers described
in element (b) are open, not closed, to blends of the recited
resins. Id.The claims themselves recite a
metallocene-catalyzed linear low density polyethylene (mLLDPE),
which is itself a subtype of LLDPE with a particular kind of
catalyst. Id. at 24. Similarly, the specification
supports construing element (b) as open to blends, as it repeatedly
and consistently references blends in describing any and all
resins, including the four resins of element (b). Id.
Similarly, the specification "repeatedly and consistently
references blends in describing any and all resins, including the
four resins of element (b)," and discusses blending the resins
in order "to achieve a desired range of physical or mechanical
properties." Id. at 25 (citation
omitted). Finding "nothing in the prosecution history to
suggest that blends are excluded," the Federal Circuit found
"this strong intrinsic evidence" requires "the
Markush group be read as open to blends of the four listed
resins." Id.

While Markush claims can give the patent applicant some freedom
to ensure full coverage of the scope of the invention, this does
not negate the right of the public to know the boundaries of the
claim. This Federal Circuit decision provides some useful
pointers on how to do so. First, carefully choose the
"generic" group for which the Markush group is offering
alternatives. As noted by Judge Taranto, Markush group
language typically recites "an X [being] selected from a group
consisting of A, B, and C," where A, B, and C are actually
instances of X. Taranto Dissent at 3 (alteration in original). That
is, the term X is a genus or generic descriptor.
Id. In this case, instead of "each
layer being selected from the group consisting of,"
the claim could have been more clear and recite "each layer
being made of a resin selected from the group consisting
of." Second, if mixtures or blends are within the scope of the
claim, be sure to say so. As noted by the court, the presumption is
that the Markush group is closed to blends and mixtures. Lastly,
avoid being the applicant that "sometimes mistakenly write[s]
dependent claims that invalidly add elements inconsistent with
their independent claims." Id. at 7. Be mindful to
draft your dependent claims, ensuring that they are narrower than
the precedent claims, and confirm that this remains consistent,
even if the scope of the independent claims is narrowed during
prosecution.

As part of the American Intellectual Property Law Association’s webinar series, Finnegan partner Beth Ferrill will moderate a discussion on the protection of unique icons and graphical user interfaces in consumer electronic devices.

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